C#: Cleanup Variant marshaling code in source/bindings generators

This change aims to reduce the number of places that need to be changed
when adding or editing a Godot type to the bindings.

Since the addition of `Variant.From<T>/As<T>` and
`VariantUtils.CreateFrom<T>/ConvertTo<T>`, we can now replace a lot of
the previous code in the bindings generator and the source generators
that specify these conversions for each type manually.

The only exceptions are the generic Godot collections (`Array<T>` and
`Dictionary<TKey, TValue>`) which still use the old version, as that
one cannot be matched by our new conversion methods (limitation in the
language with generics, forcing us to use delegate pointers).

The cleanup applies to:

- Bindings generator:
  - `TypeInterface.cs_variant_to_managed`
  - `TypeInterface.cs_managed_to_variant`
- Source generators:
  - `MarshalUtils.AppendNativeVariantToManagedExpr`
  - `MarshalUtils.AppendManagedToNativeVariantExpr`
  - `MarshalUtils.AppendVariantToManagedExpr`
  - `MarshalUtils.AppendManagedToVariantExpr`

1 files changed, 14 insertions, 47 deletions

diff --git a/modules/mono/editor/bindings_generator.cpp b/modules/mono/editor/bindings_generator.cpp
index 9185506776..9f0bc3fbe3 100644
--- a/modules/mono/editor/bindings_generator.cpp
+++ b/modules/mono/editor/bindings_generator.cpp
@@ -2837,9 +2837,6 @@ bool BindingsGenerator::_populate_object_type_interfaces() {
 		itype.is_ref_counted = ClassDB::is_parent_class(type_cname, name_cache.type_RefCounted);
 		itype.memory_own = itype.is_ref_counted;
 
-		itype.cs_variant_to_managed = "(%1)VariantUtils.ConvertToGodotObject(%0)";
-		itype.cs_managed_to_variant = "VariantUtils.CreateFromGodotObject(%0)";
-
 		itype.c_out = "%5return ";
 		itype.c_out += C_METHOD_UNMANAGED_GET_MANAGED;
 		itype.c_out += itype.is_ref_counted ? "(%1.Reference);\n" : "(%1);\n";
@@ -3218,8 +3215,6 @@ bool BindingsGenerator::_populate_object_type_interfaces() {
 			enum_itype.cname = StringName(enum_itype.name);
 			enum_itype.proxy_name = itype.proxy_name + "." + enum_proxy_name;
 			TypeInterface::postsetup_enum_type(enum_itype);
-			enum_itype.cs_variant_to_managed = "(%1)VariantUtils.ConvertToInt32(%0)";
-			enum_itype.cs_managed_to_variant = "VariantUtils.CreateFromInt((int)%0)";
 			enum_types.insert(enum_itype.cname, enum_itype);
 		}
 
@@ -3448,16 +3443,14 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 
 	TypeInterface itype;
 
-#define INSERT_STRUCT_TYPE(m_type)                                     \
-	{                                                                  \
-		itype = TypeInterface::create_value_type(String(#m_type));     \
-		itype.c_type_in = #m_type "*";                                 \
-		itype.c_type_out = itype.cs_type;                              \
-		itype.cs_in_expr = "&%0";                                      \
-		itype.cs_in_expr_is_unsafe = true;                             \
-		itype.cs_variant_to_managed = "VariantUtils.ConvertTo%2(%0)";  \
-		itype.cs_managed_to_variant = "VariantUtils.CreateFrom%2(%0)"; \
-		builtin_types.insert(itype.cname, itype);                      \
+#define INSERT_STRUCT_TYPE(m_type)                                 \
+	{                                                              \
+		itype = TypeInterface::create_value_type(String(#m_type)); \
+		itype.c_type_in = #m_type "*";                             \
+		itype.c_type_out = itype.cs_type;                          \
+		itype.cs_in_expr = "&%0";                                  \
+		itype.cs_in_expr_is_unsafe = true;                         \
+		builtin_types.insert(itype.cname, itype);                  \
 	}
 
 	INSERT_STRUCT_TYPE(Vector2)
@@ -3488,8 +3481,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.c_type_out = itype.c_type;
 	itype.c_arg_in = "&%s";
 	itype.c_in_vararg = "%5using godot_variant %1_in = VariantUtils.CreateFromBool(%1);\n";
-	itype.cs_variant_to_managed = "VariantUtils.ConvertToBool(%0)";
-	itype.cs_managed_to_variant = "VariantUtils.CreateFromBool(%0)";
 	builtin_types.insert(itype.cname, itype);
 
 	// Integer types
@@ -3510,8 +3501,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 		itype.c_type_in = itype.name;                                                          \
 		itype.c_type_out = itype.name;                                                         \
 		itype.c_in_vararg = "%5using godot_variant %1_in = VariantUtils.CreateFromInt(%1);\n"; \
-		itype.cs_variant_to_managed = "VariantUtils.ConvertTo" m_int_struct_name "(%0)";       \
-		itype.cs_managed_to_variant = "VariantUtils.CreateFromInt(%0)";                        \
 		builtin_types.insert(itype.cname, itype);                                              \
 	}
 
@@ -3547,8 +3536,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 		itype.c_type_in = itype.proxy_name;
 		itype.c_type_out = itype.proxy_name;
 		itype.c_in_vararg = "%5using godot_variant %1_in = VariantUtils.CreateFromFloat(%1);\n";
-		itype.cs_variant_to_managed = "VariantUtils.ConvertToFloat32(%0)";
-		itype.cs_managed_to_variant = "VariantUtils.CreateFromFloat(%0)";
 		builtin_types.insert(itype.cname, itype);
 
 		// double
@@ -3562,8 +3549,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 		itype.c_type_in = itype.proxy_name;
 		itype.c_type_out = itype.proxy_name;
 		itype.c_in_vararg = "%5using godot_variant %1_in = VariantUtils.CreateFromFloat(%1);\n";
-		itype.cs_variant_to_managed = "VariantUtils.ConvertToFloat64(%0)";
-		itype.cs_managed_to_variant = "VariantUtils.CreateFromFloat(%0)";
 		builtin_types.insert(itype.cname, itype);
 	}
 
@@ -3581,8 +3566,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.c_type_out = itype.cs_type;
 	itype.c_type_is_disposable_struct = true;
 	itype.c_in_vararg = "%5using godot_variant %1_in = VariantUtils.CreateFromString(%1);\n";
-	itype.cs_variant_to_managed = "VariantUtils.ConvertToStringObject(%0)";
-	itype.cs_managed_to_variant = "VariantUtils.CreateFromString(%0)";
 	builtin_types.insert(itype.cname, itype);
 
 	// StringName
@@ -3601,8 +3584,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.c_in_vararg = "%5using godot_variant %1_in = VariantUtils.CreateFromStringName(%1);\n";
 	itype.c_type_is_disposable_struct = false; // [c_out] takes ownership
 	itype.c_ret_needs_default_initialization = true;
-	itype.cs_variant_to_managed = "VariantUtils.ConvertToStringNameObject(%0)";
-	itype.cs_managed_to_variant = "VariantUtils.CreateFromStringName(%0)";
 	builtin_types.insert(itype.cname, itype);
 
 	// NodePath
@@ -3620,8 +3601,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.c_type_out = itype.cs_type;
 	itype.c_type_is_disposable_struct = false; // [c_out] takes ownership
 	itype.c_ret_needs_default_initialization = true;
-	itype.cs_variant_to_managed = "VariantUtils.ConvertToNodePathObject(%0)";
-	itype.cs_managed_to_variant = "VariantUtils.CreateFromNodePath(%0)";
 	builtin_types.insert(itype.cname, itype);
 
 	// RID
@@ -3634,8 +3613,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.c_type = itype.cs_type;
 	itype.c_type_in = itype.c_type;
 	itype.c_type_out = itype.c_type;
-	itype.cs_variant_to_managed = "VariantUtils.ConvertToRID(%0)";
-	itype.cs_managed_to_variant = "VariantUtils.CreateFromRID(%0)";
 	builtin_types.insert(itype.cname, itype);
 
 	// Variant
@@ -3652,8 +3629,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.c_type_out = itype.cs_type;
 	itype.c_type_is_disposable_struct = false; // [c_out] takes ownership
 	itype.c_ret_needs_default_initialization = true;
-	itype.cs_variant_to_managed = "Variant.CreateCopyingBorrowed(%0)";
-	itype.cs_managed_to_variant = "%0.CopyNativeVariant()";
 	builtin_types.insert(itype.cname, itype);
 
 	// Callable
@@ -3666,8 +3641,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.c_type_in = "in " + itype.cs_type;
 	itype.c_type_out = itype.cs_type;
 	itype.c_type_is_disposable_struct = true;
-	itype.cs_variant_to_managed = "VariantUtils.ConvertToCallableManaged(%0)";
-	itype.cs_managed_to_variant = "VariantUtils.CreateFromCallable(%0)";
 	builtin_types.insert(itype.cname, itype);
 
 	// Signal
@@ -3684,8 +3657,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.c_type_in = "in " + itype.cs_type;
 	itype.c_type_out = itype.cs_type;
 	itype.c_type_is_disposable_struct = true;
-	itype.cs_variant_to_managed = "VariantUtils.ConvertToSignalInfo(%0)";
-	itype.cs_managed_to_variant = "VariantUtils.CreateFromSignalInfo(%0)";
 	builtin_types.insert(itype.cname, itype);
 
 	// VarArg (fictitious type to represent variable arguments)
@@ -3715,8 +3686,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 		itype.c_type_in = itype.proxy_name;                                         \
 		itype.c_type_out = itype.proxy_name;                                        \
 		itype.c_type_is_disposable_struct = true;                                   \
-		itype.cs_variant_to_managed = "VariantUtils.ConvertAs%2ToSystemArray(%0)";  \
-		itype.cs_managed_to_variant = "VariantUtils.CreateFrom%2(%0)";              \
 		builtin_types.insert(itype.name, itype);                                    \
 	}
 
@@ -3752,8 +3721,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.c_type_out = itype.cs_type;
 	itype.c_type_is_disposable_struct = false; // [c_out] takes ownership
 	itype.c_ret_needs_default_initialization = true;
-	itype.cs_variant_to_managed = "VariantUtils.ConvertToArrayObject(%0)";
-	itype.cs_managed_to_variant = "VariantUtils.CreateFromArray(%0)";
 	builtin_types.insert(itype.cname, itype);
 
 	// Array_@generic
@@ -3761,6 +3728,9 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.name = "Array_@generic";
 	itype.cname = itype.name;
 	itype.cs_out = "%5return new %2(%0(%1));";
+	// For generic Godot collections, Variant.From<T>/As<T> is slower, so we need this special case
+	itype.cs_variant_to_managed = "VariantUtils.ConvertToArrayObject(%0)";
+	itype.cs_managed_to_variant = "VariantUtils.CreateFromArray(%0)";
 	builtin_types.insert(itype.cname, itype);
 
 	// Dictionary
@@ -3778,8 +3748,6 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.c_type_out = itype.cs_type;
 	itype.c_type_is_disposable_struct = false; // [c_out] takes ownership
 	itype.c_ret_needs_default_initialization = true;
-	itype.cs_variant_to_managed = "VariantUtils.ConvertToDictionaryObject(%0)";
-	itype.cs_managed_to_variant = "VariantUtils.CreateFromDictionary(%0)";
 	builtin_types.insert(itype.cname, itype);
 
 	// Dictionary_@generic
@@ -3787,6 +3755,9 @@ void BindingsGenerator::_populate_builtin_type_interfaces() {
 	itype.name = "Dictionary_@generic";
 	itype.cname = itype.name;
 	itype.cs_out = "%5return new %2(%0(%1));";
+	// For generic Godot collections, Variant.From<T>/As<T> is slower, so we need this special case
+	itype.cs_variant_to_managed = "VariantUtils.ConvertToDictionaryObject(%0)";
+	itype.cs_managed_to_variant = "VariantUtils.CreateFromDictionary(%0)";
 	builtin_types.insert(itype.cname, itype);
 
 	// void (fictitious type to represent the return type of methods that do not return anything)
@@ -3852,8 +3823,6 @@ void BindingsGenerator::_populate_global_constants() {
 			enum_itype.cname = ienum.cname;
 			enum_itype.proxy_name = enum_itype.name;
 			TypeInterface::postsetup_enum_type(enum_itype);
-			enum_itype.cs_variant_to_managed = "(%1)VariantUtils.ConvertToInt32(%0)";
-			enum_itype.cs_managed_to_variant = "VariantUtils.CreateFromInt((int)%0)";
 			enum_types.insert(enum_itype.cname, enum_itype);
 
 			int prefix_length = _determine_enum_prefix(ienum);
@@ -3886,8 +3855,6 @@ void BindingsGenerator::_populate_global_constants() {
 		enum_itype.cname = enum_cname;
 		enum_itype.proxy_name = enum_itype.name;
 		TypeInterface::postsetup_enum_type(enum_itype);
-		enum_itype.cs_variant_to_managed = "(%1)VariantUtils.ConvertToInt32(%0)";
-		enum_itype.cs_managed_to_variant = "VariantUtils.CreateFromInt((int)%0)";
 		enum_types.insert(enum_itype.cname, enum_itype);
 	}
 }